“THE CASSIAR STORY”

Mining

Gillyeard J. Leathley, General Mine Superintendent,
Cassiar Asbestos Corporation Limited,
Cassiar, B.C.

Abstract

The Cassiar Asbestos mine is situated on McDame
Mountain in northern B.C. at a mean elevation of 6000 ft
(1830 m), some 6 miles (9.6 km) from the townsite/mill
complex. Asbestos ore production averages 1,200,000 tons
at 9% R.M.G. (Recoverable Mine Grade) and waste produc-
tion is 6,000,000 cu. yd annually.

Waste is loaded by P&H 1900 AL 11-cu.-yd shovels and
transported by 75-ton and 85-ton end-dump trucks to the
waste dumps. The ore is loaded by a 992 Caterpillar 10-cu-yd
front-end loader into 50-ton and 75-ton trucks, which trans-
port it to the crushing plant located at the mine. The ore is
transported by a 15,370-ft (4685-m) tramline to the mill
complex.

Introduction

THE CASSIAR OPEN-PIT MINE is situated at a
mean elevation of 6000 ft (1830 m) on McDame
Mountain, 6 road miles (9.6 km) from the main mill/
plant complex. The access road rises some 2350 ft
(716 m) from the plantsite to the mine by means of
a series of tight switchbacks. Constant grading is
required with a Caterpillar 16G grader to ensure that
drainage ditches are kept clear to deal with a heavy
spring snow melt and an annual summer rainfall of
12 in. (300 mm). During winter, the grader is equip-
ped with a front snow blade, as well as a rear-mounted
hydraulically operated snow wing, and the use of tire

Gillyeard J. Leathley was born and
educated in Scotland. He graduated
from Glasgow’s Royal College of Sci-
ence and Technology, with a Higher
National Certificate in mining and
mine surveying. He joined the Na-
tional Coal Board (Scotland) in 1952
and worked as a mine surveyor and
work study engineer in underground
— coal mines. In 1962, he joined Anglo

* American Corporation, Zambia, as a
learner mine official and was later
assistant manager, Open Pit Division of AMCO, respon-
sible for open-pit coal and copper mines. Returning to
Scotland in 1967, he joined a rock excavation company
in the United Kingdom and served as a director of the
company until 1971. At that time, he became mine tech-
nical superintendent of Guyana Bauxite in South Amer-
ica, progressing to general mine superintendent in 1972.
In this position, he was responsible for the operation of
six nationally owned bauxite mines producing 5,000,000
tons of bauxite annually, with the removal of 30,000,000
cu. yds of overburden. Experience in the operation of
bueketwheel excavators, walking draglines and rail min-
ing was gained at this time.

In 1975, Mr. Leathley joined Cassiar Asbestos Corpora-
tion Limited as chief engineer. He is now general mine
superintendent responsible for the complete operation of
the engineering and mines departments. He is a member
of the CIM.

Keywords: Cassiar mine, Asbestos, Open-pit mining,
Drilling, Blasting, Lauding, Haulage, Mining methods,
Dewatering, Crushing.

chains is standard to deal with 13 ft (400 em) of
snowfall annually (Fig. 1).

Personnel are transported to the mine by a 45-seater
manhaul bus, supplemented by 4x4 pickups equipped
with 14-seat passenger carry cabs. The pickups allow
operators to change over at the equipment location,
reducing equipment downtime.

The 1977 production was 1,321,065 tons of ore and
6,874,201 cu. yds of waste rock, which meant a strip-
ping ratio of 1 ton of ore to 5.20 cu. yds of waste. The
five-year mining plan, which is updated and revised
as sales commitments and mining conditions dictate,
envisages approximately the same magnitude of ore
for the next 14 years, with waste production conti-
nuing at 6,000,000 cu. yds until Phase 9 waste is
excavated by the end of 1985.

An increase in waste-rock production, dictated by
the introduction of additional milling facilities re-
quiring an increase in asbestos ore, as well as an in-
creasing stripping ratio, led to the introduction of a
1900 AL P&H 11-cu.-yd shovel in October, 1974. An
additional 1900 AL P&H 11-cu.-yd shovel was intro-
duced in October, 1975. This necessitated pit electri-
fication, which was completed in October, 1974, and
the introduction of a fleet of 85-ton Euclid trucks.

The following figures give some indication of the
progress of the mine since production commenced in
1954:

Waste Cubic
Ore Tons Yards

TOSS OGOE An ee deerme tans 2,266,761 2,977,458
SG 0/3197 ON nares seers ce 7,907,277 17,217,172
RVR eeuissiacwone coschorte 5,376,551 13,786,669
1975 — December 1977.............. 2,244,616 13,600,575
TOIAISIREMOVED Reepetecrsecta te tepre 17,795,205 47,581,874
REMAINING TO END OF PLANNED

PT (Leos. Sbeknbodesascean anon 16,277,000 48,042,000

The phase mining plan dictates meticulous planning
of ore and waste scheduling to ensure a continuous
supply of ore to the mill, especially during the inter-
phase period. Phase mining configurations are shown
in the paper dealing with the planning operation.

The assistant mine superintendent and the general
foreman - mine, work very closely with the planning
and geology departments to ensure that long-range
plans and monthiy schedules are adhered to. It is the
responsibility of this group to ensure that adequate
ore supplies are available to blend low- and high-grade
areas or supply ore from a high-grade, long-fibre area
if a spinning-grade fibre run is required in the mill.
A planning meeting to relay this information to the
mine shift foreman is held every two weeks to allow
discussion and examination of the developed plans.
Mill requirements regarding the type and/or blending
of ore required are marked daily on a location plan in
the mine shift foreman’s office at the mine. If the
mine foreman must deviate from this plan, he is re-
quired to inform the mill shift foreman immediately
to allow the mill to relocate the ore in the dry rock
storage to a more suitable area. No designated ore
can be discarded unless agreed to by the geology de-
partment. A monthly reconciliation of ore predicted
by the geologist, and typed by him from production
drilling and actual ore mined, is carried out to ensure
that a minimum amount of ore is discarded. Unfor-

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